Studies On Genetic Marker Of Silurus Meridionalis Chen,Silurus Asotus Linnaeus And Their Hybrid F₁

The article tested the cross experiment of Silurus meridionalis Chen and Silurus asotus Linnaeus, then investigated and compared Silurus meridionalis Chen, Silurus asotus Linnaeus and their hybrid F₁ at different levels (proteins and DNA) in order to search their genetic marker and discuss their genetic affinity and heterosis. The major research results of this study are as follows:1 .Compared to the controls, the results showed that the fertility rate is little lower, hatching rate and the stocked rate have no obvious difference which suggested there was no or little breeding handicap; Through paired t-test, the growth of the hybrid F₁ is similar to control â…  and no significant difference exist between them ,but significant difference exist between the hybrid and the control â…¡, which suggested the hybrid F₁ was characterized by its faster growth rate.2. The results showed that the proteinic phenotypes of the hybrid F₁ expressed all of the parents' bands which did not have any polymorphism, while the isozymic phenotypes is very complex which inherited part of the parents and lost another part, or appeared isozymic phenotypes which did not appear in parents. The specificities of species and tissues were expressed in isozymes. Three kinds of fish had obvious polymorphism in the electrophergram of EST and ADH, especially in the electrophergram of EST. The biochemical genetic markers (EST-4)that can distinguish Silurus meridionalis Chen from the other two kinds were detected in electrophergram of EST from the kidney and spleen, also biochemical genetic markers (A₂ and B₂¹¹⁷) can be found in electrophergram of ADH from liver.3. Of these primers, 22 primers produced well-amplified and reproducible band pattern. There were 1-12 bands ranging in size from about 200 to 3500bp in the Amplified products of a single primer. After excluding bands that were not clearly identifiable, atotal of 217 distinguishable fragments were compiled for phylogenetic relationship analysis. The inter-population similarity indexes was 0. 986, 0.878 and 0.961 respectively, which showed variation in the kinds of hybrids between its parents populations. The genetic similarity index of the amplified DNA bands between the hybrid Fi and Silurus meridionalis Chen was 0.731, and that of the amplified DNA bands between hybrid Fi and Silurus asotus Linnaeus was 0.615. The similarity index of the amplified DNA bands between Silurus meridionalis Chen and Silurus asotus Linnaeus was 0.423. There are polymorphic bands within populations, the ratio of polymorphic loci are 6. 36%, 41. 13%, 15. 13% respectively. Moreover, 5 specific bands were found only in the hybrid Fi, the non-parentage bands ratio of the hybrid was 0.023. The results not only provided the specific molecular markers of the hybrid Fj, but also demonstrated that the hybrid Fi inherited a little more genetic materials from their parents. The amplified DNA bands of primers OPH-04, OPH-06, OPH-12, OPH-15, OPH-16, OPH-17, OPH-18, OPI-04, OPI-07, OPI-08, OPI-13, OPI-14 and OPI-20 can distinguish Silurus meridionalis Chen from the other two kinds.